In this letter, we incorporate index modulation (IM) into affine frequency division multiplexing (AFDM), called AFDM-IM, to enhance the bit error rate (BER) and energy efficiency (EE) performance. In this scheme, the information bits are conveyed not only by $M$-ary constellation symbols, but also by the activation of the chirp subcarriers (SCs) indices, which are determined based on the incoming bit streams. Then, two power allocation strategies, namely power reallocation (PR) strategy and power saving (PS) strategy, are proposed to enhance BER and EE performance, respectively. Furthermore, the average bit error probability (ABEP) is theoretically analyzed. Simulation results demonstrate that the proposed AFDM-IM scheme achieves better BER performance than the conventional AFDM scheme.

翻译：本文中，我们将索引调制（IM）融入仿射频率分复用（AFDM）系统，提出AFDM-IM方案，以提升误码率（BER）和能量效率（EE）性能。在该方案中，信息比特不仅通过M进制星座符号进行传输，还通过基于输入比特流激活的啁啾子载波（SCs）索引来传递。随后，我们分别提出功率重分配（PR）策略和功率节省（PS）策略两种功率分配方法，以分别提升误码率和能量效率性能。此外，对平均误比特概率（ABEP）进行了理论分析。仿真结果表明，所提AFDM-IM方案相比传统AFDM方案具有更优的误码率性能。